languagetool-org/languagetool

Style and Grammar Checker for 25+ Languages

What it solves

LanguageTool provides advanced proofreading that goes beyond simple spell checking to detect a wider range of grammatical and stylistic errors across more than 20 languages, including English, Spanish, French, German, Portuguese, Polish, and Dutch.

How it works

It operates as a core engine that can be deployed as a standalone application, a server via an HTTP API, or integrated into other software (such as LibreOffice/OpenOffice) using Java. It uses a system of error detection rules that can be contributed to by the community.

Who it’s for

It is designed for writers, developers who want to integrate proofreading capabilities into their apps, and organizations that need a self-hosted proofreading server.

Highlights

  • Support for over 20 languages.
  • Multiple deployment options: GUI, command line, and HTTP server.
  • Extensible rule-based system for error detection.
  • Open-source core available under the LGPL license.

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